A thin metal disc of radius `0.25m` and mass `2kg` starts from rest and rolls down an inclined plane. If its rotational kinetic energy is `4J` at the foot of the inclined plane, then its linear velocity at the same point is

Options

A. `1.2 ms^(-1)`
B. `2.8ms^(-1)`
C. `20 ms^(-1)`
D. `2 ms^(-1)`

Answer

B

Explanation

`KE_(rot)=1/2Iomega^(2)=1/2((MR^(2))/2)omega^(2)=(mv^(2))/4`